drm/i915: introduce page_sizes field to dev_info

drm/i915: introduce page_sizes field to dev_info

In preparation for huge gtt pages expose page_sizes as part of the
device info, to indicate the page sizes supported by the HW.  Currently
only 4K is supported.

v2: s/page_size_mask/page_sizes/

v3: introduce I915_GTT_MAX_PAGE_SIZE

Signed-off-by: Matthew Auld <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Mika Kuoppala <[email protected]>
Cc: Chris Wilson <[email protected]>
Reviewed-by: Joonas Lahtinen <[email protected]>
Reviewed-by: Chris Wilson <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Chris Wilson <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]